Acquired Digital Fibrokeratoma.

Acquired digital fibrokeratoma is a rare, benign tumor that mostly occurs on the fingers and toes and may appear to be a supernumerary rudimentary digit. It generally affects adult men and appears as a dome-shaped papule although it can also be elongated or pedunculated. Trauma is believed to be a triggering factor in some cases. We report a male patient with an acquired digital fibrokeratoma on a finger, shaped like a cutaneous horn, and a history of minimal repeated trauma and spontaneous remissions not previously described in the literature.

Concomitant Subtypes of Granuloma Annulare in a 66-Year-Old Female: A Case Report.

Granuloma annulare (GA) is a benign, self-limited inflammatory skin condition with an unknown etiology. Although it usually presents with characteristic clinical features, a biopsy may be necessary in atypical cases to differentiate it from other granulomatous diseases. We describe a case of a 66-year-old female with two concomitant subtypes of GA, presenting with distinct clinical features but exhibiting similar histopathological findings. The patient had extensive, pruritic erythematous-violaceous lesions on her lower abdomen, buttocks, and proximal thighs, which had been progressing over the course of one year. Biopsies from the abdominal and thigh lesions showed typical histopathological features of GA, with mucin deposition, histiocytic infiltrate, and granulomatous formations. Treatment with oral antihistamines and medium-potency topical corticosteroids effectively controlled the itching but did not alter the lesion's appearance. Five months later, the patient developed new, pruritic, skin-colored, confluent papules on the internal face of her left arm, and a subsequent biopsy confirmed annular GA. Although the patient did not follow the prescribed dapsone treatment, the lesions spontaneously regressed within a year. This case emphasizes the importance of recognizing less common presentations of GA, which can mimic other, more concerning conditions. While various therapeutic options have been explored, none guarantee complete remission; however, GA typically resolves on its own over time. A better understanding of the disease's pathogenesis and the development of targeted treatments are warranted to improve management strategies for GA.

Pigmentary Demarcation Lines During Pregnancy With Erythema.

Pigmentary demarcation lines (PDL), or Voigt-Futcher lines, are lines that mark an abrupt transition between hyperpigmented skin and normal skin. PDLs are more common in Japanese and dark-skinned individuals. Eight types have been described (A-H); Type B is located on the posteromedial aspect of the lower extremities; it is more common in women and is the one most frequently associated with pregnancy. The demarcation lines of pregnancy are of unknown etiology; they appear mainly in the last trimester and disappear spontaneously months after delivery. We report a case of pregnancy-associated PDL with erythema without melanocytic pigmentation in a 23-week-gestational Latin primiparous woman.

Superficial Angiomyxoma in an Uncommon Area: A Case Report.

Superficial angiomyxomas, also known as cutaneous myxomas, are rare, benign soft tissue tumors that present as papulonodular or polypoid, asymptomatic, slow-growing lesions. They typically occur in the head, neck, trunk, and extremities of adults and may be isolated tumors or part of the Carney Complex. We present a case of SA with an uncommon area of presentation and a brief discussion of the importance of ruling out the presence of systemic syndromes such as the Carney Complex.

Refractive index spectroscopy and material dispersion in fused silica glass.

In this study, we aimed to measure material dispersion in fused silica using a low coherence interferometric method. The measurement was carried out quickly and efficiently in a wide spectral range using this method. The refractive index and group index of fused silica were determined by capturing a few interferograms. The material dispersion was modeled using a Sellmeier equation with three resonances. Three different fits were investigated; the most appropriate fit was the one that used both the measured refractive and group indexes to model the dispersion. Second-order dispersion was also quantified, and zero-dispersion wavelength was determined.

An experimental and computational study on the material dispersion of 1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids.

The material dispersion of the [Ckmim][BF4] (k = 2, 3, 4, 6, 7, 8, 10) family of ionic liquids is measured at several temperatures over a broad spectral range from 300 nm to 1550 nm. The experimental curves are fitted to a modified three-resonance Sellmeier model to understand the effects of temperature and alkyl chain length on the dispersion behaviour. From the parameters of the fitting, we analyze the influence that the different constituents of these ionic liquids have on the dispersion behaviour. In addition, a semi-empirical approach combining simulated electronic polarizabilities and experimental densities for predicting the material dispersion is successfully tested by using a direct comparison with the experimental results. The limitations of this method are analyzed in terms of the molecular structure of the ionic liquids. The results of this work aim to increase our knowledge about how the molecular structure of an ionic liquid influences its material dispersion. Understanding this influence is fundamental to producing ionic liquids with tailored optical properties.

Conocimiento y conductas de protección solar de pescadores en Chile / Knowledge and sun protection behaviors of fishermen in Chile

INTRODUCCIÓN: La sobreexposición a la radiación ultravioleta (RUV) es un factor de riesgo importante para el desarrollo de cáncer de piel (CP). Aquellos trabajadores que realizan labores al aire libre, como los pescadores, son un grupo de riesgo, por lo que es importante saber si tienen los conocimientos y realizan las conductas que les permitan protegerse de la RUV. OBJETIVO: Evaluar en un grupo de pescadores el conocimiento respecto a los riesgos de la exposición solar y sus conductas respecto a medidas de protección solar. MATERIAL Y MÉTODOS: Los datos fueron obtenidos por encuestas a 133 pescadores. Se obtuvieron antecedentes sociodemográficos y se aplicó un cuestionario de 11 preguntas para evaluar conocimiento sobre riesgos de la RUV y conductas de fotoprotección. RESULTADOS: La cohorte incluyó a 133 pescadores, todos fueron hombres con edad promedio de 48 +/- 11,2 años. Un 86% de los pescadores conocía la relación entre exposición solar/CP. En cuanto al uso de filtro solar (FS), un 54,8% de los trabajadores reportó nunca haberlo utilizado y un 41% lo hacía solo una vez al día. Los pescadores con escolaridad incompleta presentan 2,6 veces menor probabilidad de utilizar FS (OR 2.6; p<0.05). Además, aquellos con conocimiento de la relación RUV y fotoenvejecimiento, presentaban 3,75 veces más probabilidad de utilizar FS (OR 3.75) (p<0.05). CONCLUSIÓN: Este primer estudio sobre protección solar en pescadores muestra que la mayoría están en conocimiento de los riesgos a la salud. Sin embargo, no utilizan las medidas de protección recomendadas y aquellos que las utilizan, no lo hacen de la manera adecuada.

INTRODUCTION: Overexposure to ultraviolet radiation (UVR) is the main risk factor for the development of skin cancer (SC). Outdoor workers, such as fishermen are a risk group. Therefore, it is important to study if they have the knowledge towards sun exposure and also to know their solar protection behaviors. OBJETIVE: To evaluate in a group of fishermen if they have the knowledge about the risks of solar exposure and their behavior regarding sun protection measures. MATERIALS y METHODS: Data was obtained from a survey applied to 133 fishermen. Collected information included sociodemographic characteristics and 11 questions about knowledge and their sun protection measures. RESULTS: The cohort included 133 fishermen, all were male with an age average of 48 +/- 11,2 years. 86% knew about the relation between solar exposure and skin cancer. When asked about sunscreen use, 54.8% declared they never used it and 41,0% did only once a day. The fishermen who had incomplete secondary school studies were less likely to use sunscreen (OR 2.6) (p<0.05). Those who had knowledge of the relation between UVR and aging were 3,75 times more likely to use sunscreen. CONCLUSION: This is the first study about solar protection knowledge and photoprotection measures upon fishermen, performed in Chile. Most fishermen were aware of the health risks. However, they do not use the recommended protection measures, and those who use them, do not do it properly

Refractive index measurements in absorbing media with white light spectral interferometry.

White light spectral interferometry is applied to measure the refractive index in absorbing liquids in the spectral range of 400-1000 nm. We analyze the influence of absorption on the visibility of interferometric fringes and, accordingly, on the measurement of the refractive index. Further, we show that the refractive index in the absorption band can be retrieved by a two-step process. The procedure requires the use of two samples of different thickness, the thicker one to retrieve the refractive index in the transparent region and the thinnest to obtain the data in the absorption region. First, the refractive index values are retrieved with good accuracy in the transparent region of the material for 1-mm-thick samples. Second, these refractive index values serve also to precisely calculate the thickness of a thinner sample (~150 µm) since the accuracy of the methods depends strongly on the thickness of the sample. Finally, the refractive index is recovered for the entire spectral range.

Spectrally resolved white light interferometry to measure material dispersion over a wide spectral band in a single acquisition.

In this paper we apply spectrally resolved white light interferometry to measure refractive and group index over a wide spectral band from 400 to 1000 nm. The output of a Michelson interferometer is spectrally decomposed by a homemade prism spectrometer with a high resolution camera. The group index is determined directly from the phase extracted from the spectral interferogram while the refractive index is estimated once its value at a given wavelength is known.

White light spectral interferometry as a spectrometer calibration tool.

For this paper, we used a white light interferometer in combination with spectral lamps to perform the wavelength calibration of a dispersive spectrometer. Illuminating the spectrometer with suitable spectral lamps gives the wavelength-pixel number relationship at discrete positions of the spectrometer detector array, and the wavelength-dependent phase difference at the output of the white light interferometer allows for a complete spectral calibration at any point on the detector (i.e., for every wavelength in the spectral range of the spectrometer). The details of this new calibration procedure are discussed, and two practical examples exhibiting the robustness of the method are presented. In addition, certain issues relating to minimizing the number of spectral lines used in the calibration procedure are examined.

Pupil aberrations in Offner spectrometers.

The light path function (LPF) of an Offner spectrometer is presented. The evaluation of the LPF of this spectrometer enables its imaging properties to be studied for arbitrary object and image positions, while avoiding the more complicated analysis of intermediate images generated by the diffraction grating, which is often involved. A power series expansion of the LPF on the grating coordinates directly determines pupil aberrations of the generated spectrum and facilitates the search for configurations with small low-order aberrations. This analysis not only confirms the possibility of reducing low-order aberrations in Rowland-type mounts, namely astigmatism and coma, as predicted in previous studies, but also proves that all third-order terms in the series expansion of the aberration function can be canceled at the image of the design point and for the corresponding design wavelength, when the design point is located on a plane orthogonal to the optical axis. Furthermore, fourth-order terms are computed and shown to represent the most relevant contribution to image blurring. Third- and fourth-order aberrations are also evaluated for Rowland mounts with the design point located outside the aforementioned plane. The study described in this manuscript is not restricted to small angles of incidence, and, therefore, it goes beyond Seidel and Buchdahl aberrations.

Design of Dyson imaging spectrometers based on the Rowland circle concept.

We aim to show that Dyson imaging spectrometers can be easily designed by applying the concept of the Rowland circle to refracting surfaces. This allows us to conceive an analytical procedure that is based on the removal of astigmatism at two wavelengths. Following this procedure, high-optical-quality spectrometers can be designed even for high speeds. Root-mean-square spot radii less than 2.5 µm are obtained for speeds as high as f/1.5, slit lengths of 15 mm, and wavelength ranges of 0.4-1.7 µm. Design examples are presented for classical Dyson spectrometers in which the detector is glued to the glass plane surface and for spectrometers with an air gap between this surface and the image plane.

Off-plane anastigmatic imaging in Offner spectrometers.

In this paper, the imaging performance of an Offner concentric imaging spectrometer is analyzed when the spectrometer entrance slit is disposed arbitrarily on the plane that is parallel to the grating grooves and contains the common center of curvature. Astigmatism-corrected designs are obtained for off-plane incidence on the grating if one point on the slit is located on the Rowland circle of the primary mirror. In this case, the combined system of primary mirror plus diffraction grating provides two astigmatic line images oriented parallel and orthogonal to the plane of diffraction, with the former located on the same plane as the slit. Consequently, these images can be brought to a single focus on this plane by the tertiary mirror if its radius of curvature is chosen properly. In addition, coma aberration is simultaneously removed. These results can be applied to the design of two-mirror or three-mirror spectrometers, generalizing the concept of the best imaging circle and providing solutions to get anastigmatic imaging for two object points and two wavelengths.

Schwarzschild spectrometer.

This is a proposal and description of a new spectrometer based on the Schwarzschild optical system. The proposed design contains two Schwarzschild optical systems. Light diverging from the spectrometer entrance slit is collimated by the first one; the collimated light beam hits a planar diffraction grating and the light dispersed from the grating is focused by the second system, which is concentric with the first. A very simple procedure obtains designs that are anastigmatic for the center of the slit and for a particular wavelength. A specific example shows the performance of this type of spectrometer.

The Offner imaging spectrometer in quadrature.

This is a proposal and description of a new configuration for an Offner imaging spectrometer based on the theory of aberrations of off-plane classical-ruled spherical diffraction gratings. This new spectrometer comprises a concave mirror used in double reflection and a convex reflection grating operating in quadrature, in a concentric layout. A very simple procedure obtains designs that are anastigmatic for a given point on the entrance slit and a given wavelength. Specific examples show that the performance of this type of system improves the performance of analogous conventional in-plane systems, when compactness and/or high spectral resolution is of fundamental importance.

Two-wavelength anastigmatic Dyson imaging spectrometers.

High-quality Dyson imaging spectrometers are designed by applying a telecentric condition for off-axis image points. By imposing this condition for two different wavelengths, designs presenting low aberrations for the whole spectral range of the system are obtained. A UV-TO-NIR fast design (f/1.5) exhibiting excellent optical performance is presented.

Imaging with classical spherical diffraction gratings: the quadrature configuration.

We review the theory of spherical diffraction gratings with regard to their imaging properties in off-plane arrangements. Our study is restricted to gratings with equally spaced grooves, and it is focused on the quadrature configuration, where the incident and diffraction planes are orthogonal to each other. We identify regions of low astigmatism and propose some monochromator mounts.

Amplitude and phase reconstruction by radial shearing interferometry.

We describe a new procedure for retrieving both amplitude and phase of an optical beam from radial shearing measurements. Information from the sheared interferogram is used to estimate and improve the beam and wavefront shape in successive iterations. We present computer simulations and experimental results that show the performance of the method.

Mach-Zehnder diffracted beam interferometer.

We use a Mach-Zehnder interferometer with two afocal systems to generate the interference between an image and a diffracted copy of a test beam. The interference data is inserted in an iterative algorithm for phase retrieval. We carry out a numerical study of the performance of this wavefront reconstruction technique with simulated data and we present also experimental results obtained using several lenses as test objects.